A gender non-binary person trying to correct the sex on their birth certificate has spent six months communicating with the Births, Deaths and Marriages office, with little success.

Jess Mio. Photo: RNZ / Anusha Bradley

Napier curator Jess Mio, 29, whose pronouns are "they/them", was labelled female at birth by staff at the hospital where they were born in 1989. But Mio says that by doing so, staff concurrently assigned the wrong gender.

In August last year, Mio contacted Births Deaths and Marriages about changing the sex on their birth certificate from "female" to "X", meaning unspecified.

Mio needed to use their amended birth certificate to apply for a PhD scholarship by 1 October, last year.

But with that deadline now long passed, Mio is still stuck with incorrect documentation, making them feel "like a fraud". They want their birth certificate to be consistent with their passport and driver licence, which both list their sex as 'x'.

In August, Mio was told by the Births, Deaths and Marriages office to provide a letter from the hospital where they were born, stating their birth certificate was incorrect and the sex should be changed from 'female' to 'x'.

But the hospital no longer holds their birth record, and told Mio their GP was best placed to provide a letter to confirm their sex.

Mio then sent the office of Births, Deaths and Marriages a letter from their GP confirming they were non-binary, as well as a statutory declaration signed by a Justice of the Peace.

But the office declined their application due to insufficient evidence, leaving Mio unsure what evidence was sufficient.

"It's a very obscure process," Mio said. "It's not defined as to what you need to go through in order to get an X on your birth certificate."

In October, six weeks after their initial application to change their birth certificate, Mio still had no indication from the office about when the problem would be resolved, and a lack of communication meant five different response timeframes set by the office had not been met.

Mio laid a complaint with the office, which was not responded to until 18 January - three months later - when the deputy registrar general apologised for the delay.

Mio has now been told that a letter from the hospital where they were born confirming that their sex, rather than gender, was recorded incorrectly, and a letter from their GP saying the same, may constitute sufficient evidence.

Births, Deaths and Marriages Registrar General Jeff Montgomery told RNZ that Mio's case is complex, with only one similar request in the last seven years.

He says an error may have been made when Mio was born, but only the hospital can correct that error.

"We'd like to help Jess achieve what they're seeking to achieve. Unfortunately we do need to work within the law as it's currently written, and it is quite constraining on what we're able to do," Montgomery said.

For Mio, and many other gender diverse people, having the wrong sex on their birth certificate undermines their identity.

To change the sex on your birth certificate, you must apply through the Family Court and provide proof you've had medical treatment, or do what Mio is trying to: go through the Births, Deaths and Marriages with proof an error was made.

This is at odds with the process for changing a New Zealand driver licence or passport, which is done by statutory declaration.

A Bill that will enable gender diverse people to change the sex on their birth certificate by statutory declaration is due for its second reading in Parliament early this year.